Struktur Data

Stack

M. Kautsar SophanT. Informatika Unijoyo

Ref:Algorithms and Data Structures in C++, Allan Parker, CRC Press, 1993 chap 3.3Beginning Algorithms, Simon Haris, James Ross, Wiley Publishing, 2006 chap 5

OutlineStack

Intro Operasi Penggunaan

real-world examples of stacks Plates are usually stacked—you place

the first one on the shelf and add to the top. If you need a plate, you remove the top

one first

A stack is like a list with access restricted to one end

Stack Astack both inserts (pushes) and

deletes (pops) from the top data structure used to store and

retrieve data supports two operations push and pop.

The push operation places data on the stack and,

the pop operation retrieves the data from the stack

STACK LIFO, data baru diletakkan di atas data

yang terakhir

Data 1

Data 2

Data 3

Data 4

Stack Data masuk/keluar dari 1 pintu Penyajian

Dgn Array (jml elemen statis) Dgn Linked List

Operasi Stack Push, Adds a value to the top of the stack.

The size of the stack will increase by one Pop, Deletes and returns the value at the top

of the stack. The size of the stack willdecrease by one. Throws EmptyStackException when there are no more elements on the stack.

Size, Obtains the number of elements in the stack.

Peek, Returns but does not delete the value at the top of the stack. Throws EmptyStackException when there are no elements on the stack.

isEmpty, Determines whether a stack is empty

Clear, Deletes all elements from a stack. The size of the stack is reset to zero.

Push

Pop

Sekilas tentang Class in Java In the real world, you'll often find many individual

objects all of the same kind. There may be thousands of other bicycles in

existence, all of the same make and model. Each bicycle was built from the same set of

blueprints and therefore contains the same components.

In object-oriented terms, we say that your bicycle is an instance of the class of objects known as bicycles. A class is the blueprint from which individual objects are created

Class in Java Class memiliki

Atribut / variabel Methode

Fungsi Prosedur / void

Stack – contoh penyajian

Operasi Push

Operasi Pop

Beberapa kegunaan stack Mengecek ekspresi matematis Notasi Polish Mencatat address dalam operasi

memory

Mencek ekspresi numerik.34 * 10

Operand

Operator

Operator PrecedenceTingkat presedensi operator, dari rendah

ke tinggi Or Xor And + - * / %

Operator Precedence 1 + 5 * 3 = ?? (1 + 5) * 3 = ??

Mencek ekspresi numerik.Looping sepanjang ekspresi, R = ekspresi[I] If R operand,

If top stack operand kosong, push R ke stack operand Else,

If top stackoperator kosong, ekspresi salah. Else, join pop stack operand + pop stack operator + R

Push ke stack operand

IF R operator push R ke stack operator. Jika (, push ke stack_kurung Jika ), join: pop operand + pop operator + pop operan,

push to operandpop (

Jk stack operator kosong, dan stack operand = 1, stack_kurung kosong, ekspresi benar

Ekspresi Numerik Infix/penulisan standar

contoh: ( 3 + 5 ) * 7 – (34 / 54))4 – 5

Notasi polish Prefix

- 4 5 Postfix/suffix

4 5 -

Operand

Operator

Notasi Polish Infix, dengan susunan operator diantara 2

operandeg: 1*2, (1*2)+3 = 1*2+3

Postfix, dengan susunan operator setelah operand utk menghitung expresi matematiseg: 12*, 12*3+

Prefix, dengan susunan operator sebelum operandeg: *12, +*123

Konversi? Infix : (6+7)* ((6-23)/10)+4 Postfix? Prefix? Infix: 8+6-3/89 Postfix? Prefix?

Algoritma Infix Postfix ??Looping sebanyak ekspresi. R=ekspresi[I] If R operand, langsung tulis If R kurung buka, push ke stack If R kurung tutup, pop until ‘(‘. Tulis semua hasil

pop kecuali ‘(‘ If R operator,

If stack kosong atau R lebih tinggi dari top stack, push R ke stack

Else pop top stack dan tulis. Ulangi perbandingan R Tulis sisa stack

Latihan Notasi Polish1. 5 + 6 * 22. 8 – ( 8 * 2 )3. ( 8 + 3 ) + [ ( 2 + 3 + 2) – 2 ]4. ( 4 – 3 / 2 * 2 ) + 2

Tugas1. Buat Program utk membalik kata.

Contoh: Budi makan pagi pagi makan Budi

2. Buat implementasi Stack, dengan fungsi push, pop, size, peek, isEmpty, clear, PrintStack

3. Buat program utk konversi

1. Infixe ke prefix

2. Prefix ke infix

3. Postfix ke infix

4. Infix ke postfix